I2C on Arduino Connector not working



I am building a demo with the MangOHGreen board and a HL7692 in the CF3 socket.
No problem so far. The Arduino sketch works with out problem also the communication from the Arduino is working.
I want to connect a 1.5inch OLED to the Arduino with I2C.

But when connecting anything on the I2C board (on both available pin locations for I2C). I know that the Leonardo I2C pinning is different than a standard Arduino but my I2C sketch is workings on a original Leonardo board.
When my sketch stripped to minimum the I2C still doesn’t work.

I have two MangOH Green boards, and both are not working.

Anybody experience with this?

Regards, Frans


What pin numbers are you trying to connect for I2C?


I used pin 10 (SCL) and pin 9 (SDA) on CN1501.

But I found the mistake. The text with the pin description next to the connector is not correct.
The labeling start at the second pin and not at the first pin.
So everything is one off on the side of CN1500 abd CN1501. I trusted the text next to the connector. I measured -1.7V on the display as the GND was actually the 5Volt and the 5Volt was the 3.3V.

It is working great now. Nice small oled display to see the cat-1 module working on the network.

Regards, Frans